Research is directed to elucidating the ion channel properties of colicins K and E1, which abolish the membrane potential of the cells they act upon. Major effort will be devoted to elucidating the conductance for ions (except protons) created by these colicins in artificial membranes and the basis of the selectivity. We are studying mutant colicins that enter membranes but do not create ion channels. Purified colicins will hopefully be crystallized and their structure analysed in terms of their function. A project made possible by a new method synchronizing colicin induction in colicinogenic cells will be to analyze the membrane aspects of colicin production and release.